The present invention relates to the alignment of vehicle components relative to one or more features of a vehicle, and in particular, to methods and apparatus for adjusting the alignment of vehicle collision avoidance systems with the travel direction of the vehicle using machine vision components.
Machine vision vehicle wheel alignment systems have been in use by the vehicle service industry for several years. A typical machine vision vehicle wheel alignment system, such as the Series 811 wheel alignment system, configured with the DSP600 sensors manufactured by Hunter Engineering Co. of Bridgeton, Mo. consists of a console unit, cameras, and optical targets. The console unit contains a computer configured with image processing and vehicle wheel alignment software applications, and incorporates various operator interfaces, including a keyboard, a mouse, a printer, and a display device. The cameras are coupled to the computer, and the optical targets are disposed in the field of view of the cameras, typically mounted to the wheels of a vehicle undergoing an alignment inspection.
Commonly, to view the left and right sides of a vehicle, two or more cameras are disposed on opposite sides of the vehicle, each having a field of view encompassing one or more wheels of the vehicle. In alternative configurations, two cameras are provided on each side of the vehicle, each having a field of view encompassing a single vehicle wheel, i.e. a left front, left rear, right front, and right rear wheel, respectively. To facilitate vehicle wheel alignment, optical targets are mounted on the vehicle wheels, and observed by the cameras. The optical targets preferably have predetermined features which are identified in images obtained by the cameras, and which facilitate a determination of the position and orientation of the optical targets. The image processing may either take place in the camera modules, or in the console computer. Once the position and orientation of each optical target is determined, the position and orientation of the associated vehicle wheel can be determined, and corresponding, the various vehicle wheel alignment angle measurements may be either determined or calculated. These angles typically include camber, caster, and toe angles for each vehicle wheel, the vehicle centerline, and the vehicle rear thrust line.
It is becoming increasingly common for automotive vehicles to be equipped with adaptive cruise control systems which include forward-looking collision avoidance radar components. Collision avoidance radar components, such as those manufactured by Robert Bosch GmbH of Germany, typically operate in either a frequency modulation (FM) or continuous wave (CW) mode to transmit a signal from an antenna typically located in the front grill area of an automobile. The collision avoidance radar then determines from the return signal received by the antenna a distance an object causing the return signal is located from the automobile and the rate of closure of the object. Systems in the United States of America are currently configured to operate within a 76-77 GHz frequency band allocated by the Federal Communications Commission (FCC) for collision avoidance radar systems. However, other collision avoidance systems may be constructed which operate within different portions of the electromagnetic spectrum, for example, utilizing infrared or visible light lasers to obtain information about objects in the path of a vehicle, or alternatively, utilizing ultrasonic signals.
To obtain an accurate measure of the distance between the vehicle on which the collision avoidance components are mounted and an object from which emitted radar or laser signals are reflected, it is necessary to ensure that the emitted signals are transmitted along the same vector as the vehicle is traveling, which is typically the vehicle rear thrust line for straight-line motion. Any misalignment between the transmission vector and the direction of vehicle travel may result in misidentification of approaching objects, a miscalculation of the distances between the vehicle and the object, and accordingly, a miscalculation of the rate of closure between the two. Depending upon the severity of the miscalculation, the collision avoidance components might fail to recognize an impending collision, or in the case of adaptive cruise control systems, might signal a reduction in vehicle speed which is less than that which is required to safely avoid a collision.
Conventionally, the manufacturer of the vehicle collision avoidance system provides a vehicle service apparatus specifically designed to facilitate the alignment of the signal emitting and receiving components. Examples of vehicle service apparatus designed to facilitate the alignment of collision avoidance systems can be found in U.S. Pat. No. 6,363,619 B1 to Schrimer et al. and in U.S. Pat. No. 6,583,868 B1 to Hopfenmuller. Typically, a collision avoidance system alignment fixture is placed in front of the vehicle, and configured with components to facilitate a precise placement relative to the vehicle. These may include alignment marks onto which lasers are projected from vehicle mounted laser pointers, i.e., as shown in the '868 Hopfenmuller patent, or alignment mirrors as shown in the '619 Schrimer et al. patent. Alternatively, the collision avoidance system alignment fixture may include mounting points for traditional transducer-based vehicle wheel alignment sensor heads. Preferably, these mounting points are perpendicularly disposed to a steer axis of the collision avoidance system alignment fixture, generally defined by as the centerline of the fixture. The mounting points are preferably spaced apart from the collision avoidance system alignment fixture on extension arms, such that each is approximately disposed outward of the vehicle's sides to facilitate reference to similar sensor heads attached to the vehicle wheels.
Once the vehicle wheels have been properly aligned, or the vehicle wheel alignment angles including the rear thrust line have been measured with the traditional transducer based vehicle wheel alignment sensor heads, wheel alignment sensor heads are removed from the front wheels of the vehicle, and placed on the mounting points on the collision avoidance system alignment fixture. With the mounting points disposed outward of the vehicle's sides, the traditional transducer-based vehicle wheel alignment sensor heads removed from the front wheels may still cooperate with the vehicle wheel alignment sensor units which remain mounted to the rear wheels of the vehicle to determine a relative alignment between the collision avoidance system alignment fixture and the vehicle rear thrust line.
Accordingly, it would be highly advantageous to facilitate the placement of alignment fixtures of a vehicle collision avoidance system relative to the direction of travel of the associated vehicle, using components of a machine vision vehicle wheel alignment system, thereby eliminating the need for vehicle service centers to either delay acquiring machine vision vehicle wheel alignment systems or maintain both a machine vision vehicle wheel alignment system and a conventional transducer-based vehicle wheel alignment system for purposes of aligning vehicle collision avoidance systems.
It would be further highly advantageous in some applications to facilitate the placement of a vehicle service apparatus, such as a headlight aiming device or sensing devices for providing driving assistance such as Intelligent Vehicle Highway Systems, relative to an associated vehicle undergoing a vehicle service procedure using components of a machine vision vehicle wheel alignment system, thereby eliminating the need for additional or supplemental alignment equipment or procedures.